Conventionally, the internal combustion engine is equipped with a Hall effect sensor as a signal element in a signal generator (as shown in FIG. 7). In order to save space, the signal element mounting plate A1 is fastened around a bearing block A3 of a shaft A2 by means of the inner surface of the center hole of the mounting plate A1. If the bearing block A3 is furnished with at least three ribs, the signal element mounting plate A1 will be able to mount on the bearing block; such mounting method has the advantage of requiring less space, but the disadvantages are that: (1), since the signal element mounting plate is mounted around the bearing block by means of the inner surface of the center hole thereof, the fastening area and the moment of force are limited, i.e., the external diameter of the signal element mounting plate being unable to increase; otherwise, a vibration may result; (2), since the external diameter of the signal element mounting plate can not be increased, the distance between the signal element and the center of the shaft is very small, and therefore the timing signal generated by the rotation of the vane type rotor across the signal element has a poor resolution and precision; (3), since the bearing block is mounted under the bottom of the distributor, the difficulty and cost of installation of the signal wires from the signal element to the signal-output socket fastened to the housing become higher than normal; (4), when the conventional design is used, the bearing block is mounted under the signal element mounting plate, and there will be no space for the signal element; consequently, it would not work well when used in an advanced engine management system (i.e., two signal elements on a signal generator to produce two timing signals); (5), the conventional design has no stray noise isolating plate, and the signal it generates is not suitable to be used in a micro-computer control system.